Method of making a multilayer plastic chip capacitor

ABSTRACT

Multilayer chip capacitors and method of making whereby two-side metalized plastic strip material is wound in annular hoop form and opposite sides of hoop are pressed together to bond layers together. The metalized plastic strip is pre-coated with a very thin coating of a heat sealable material such as plastic which functions as a capacitor dielectric and also as a bonding agent. The marginal edges of the pressed hoop are sprayed with molten aluminum at high velocity which makes contact with the edges of the thin metalized layers and penetrates the plastic coating to also provide contact with marginal portions of the metalized electrode coatings. The flattened hoop is then sliced into a plurality of capacitors which can be made to have any value desired over a large range by cutting them to a particular width. Values can be controlled very precisely by first cutting and testing one capacitor and then altering the width of later cut capacitors relative to the tested one. The uncut capacitors can be stored and cut to value as needed.

0 United States Patent 11 1 1111 3,731,354

Rayburn 1 May 8, 1973 54 METHOD OF MAKING A 3,214,657 10 1965 Davis..317/258 MULTILAYER LA P 3,327,184 6 1967 Valley ..317/258 CAPACITOR1,173,452 2/1916 Meirowsky...'. ..317/261 [75] Inventor: Charles C.Rayburn,.Falls Church, Primary Examiner charles Lanham AssistantExaminerCarl E. Hall [73] Assignee: Illinois Tool Works Inc., Chicago,yh m Buckman 6t 111. [22] Filed: Mar. 10, 1972 [57] ABSTRACT Multila erchi ca acitors and method of makin [2]] App! 233825 whereb two-s i dersetalized plastic strip material 1% Related Application Data wound inannular hoop form and opposite sides of hoop are pressed together tobond layers together. [62] Dmsmn of 40912 May 1970' The metalizedplastic strip is pre-coated with a very thin coating of a heat scalablematerial such as plastic which functions as a capacitor dielectric andalso as a 52 u.s.c1. ..29/2s.423, l279/246107,321970529631, bondingagent. The marginal edges f the press'ed 51 1111. c1. ..H0lg 13/00 aresprayed alummum [58] Field of Search ..29/25.42, 593, 417; which makeswith edges the 317/258, 260, 261, 242 thin metalized layers andpenetrates the plastic coating to also provide contact with marginalportions of [56] Reerences Cit-ed the metalized electrode coatings. Theflattened hoop is thensliced into a plurality of capacitors which canUNITED STATES PATENTS be made to have any value desired over a largerange 3 506,895 4/1970 Kellerman ..29/25.42 x by cutting them to aParticular values can be 3:670378 6/1972 Behn et a1 "29/2142 controlledvery precisely by first cutting and testing 2,731,705 55 Grouse u29/2542 one capacitor and then altering the width of later cut 2,731,7061/1956 Grouse ..29/25.42 capacitors relative to the tested one. Theuncut 2,785,352 3/1957 Netherwood... ..29/25.42 X capacitors can bestored and cut to value as needed. 3,364,401 H1968 Rayburn ..29/25.42 X2,921,246 l/1960 Peck et al ..317/260 13 Claims, 19 Drawing FiguresPATENTEDHAY' 191s SHEET 1 [1F 2 IIIIIIIPII.

PATENTED 8W3 SHEET 2 OF 2 fllyllllll l lllllI/l b METHOD OF MAKING AMULTILAYER PLASTIC CHIP CAPACITOR This is a division, of applicationSer. No. 40,012, filed May 25, 1970 now US. Pat. No. 3,654,532.

BACKGROUND OF THE INVENTION A rolled capacitor made from two-sidemetalized polyester film material, having a heat sealable coating ofplastic material applied to each of the metalized layers for holding thecapacitor together and to exclude air from between the layers isdescribed in U.S. Pat. No. 3,214,657. Although the rolled capacitordescribed in the aforementioned patent has many advantages, it hascertain disadvantages common to all rolled capacitors in that eachcapacitor must be separately rolled and mounted for lead attachment.Furthermore, where different values of capacitance are desired, thelength and/or width of the region of overlapped electrodes must bevaried during the winding of the capacitors. Another disadvantage of arolled-type capacitor is that it cannot be directly connected to aprinted circuit board or substrate without first having leads attachedto it.

In US. Pat. No. 2,731,706, a method of making capacitors is shownwherein a pair of strips of one-side metalized plastic film are wound inannular form about a forming ring. After several convolutions of filmare placed on the forming ring, the ends of the film are sealed and theforming ring, with the convolutions of film attached to it is removedfrom the winding machine and subjected to several operations includingthe cutting apart of individual capacitors.

It is an object of this invention to provide a plastic chip capacitorwhich can provide sufficient capacitance in a given volume so as tocompare favorably with ceramic chip capacitors or wet Tantalumelectrolytic capacitors.

It is a further object of the invention to provide a plastic chipcapacitor which, as compared to high K multilayer ceramic capacitors,offers a lower voltage coefficient, a lower temperature coefficient,freedom from capacitance aging, and self-healing properties.

An additional object of the invention is to provide a chip capacitorwhich will have a very low material cost, will provide excellent yieldcontrol, shorter production cycles, lower equipment investment and lowermaterial inventory cost than other types of capacitors now available.

The preceding and other objects are obtained by the capacitor of thepresent invention and the method by which it is made. The capacitorcomprises a plurality of layers of two-side metalized plastic dielectricmaterial which has had a very thin coating of dielectric such as plasticapplied to at least one of its metalized surfaces. For ease ofmanufacture, it is preferable that the plastic coating material extendsto the edges of the capacitor. Since the metal electrodes which areformed by vapor depositing aluminum are extremely thin, it is obviousthat there is extremely little electrode surface exposed at the end ofthe capacitor to which a terminal may be attached. It is also obviousthat good contact must be made between each of the alternate electrodelayers which extend to a common end of the capacitor in order to placeall of the electrodes in the electric field. I have found thatsatisfactory contact to each layer can be made by subjecting the ends ofthe capacitor to a high velocity spray of molten metal, preferablyaluminum, which embeds itself in the plastic coatings between themetalized layers so as to contact the surface as well as the ends of theelectrodes, but does not substantially penetrate the plastic dielectricstrip so as to permit a shorting out of the electrodes of oppositepolarity thereon which are spaced interiorly of the ends of thecapacitor.

The preferred method for making the plastic chip capacitor as describedherein is to wind the plastic coated metalized dielectric material abouta large diameter mandrel so as to form a hoop. The hoop may be heatsealed along a line to anchor the outermost convolution. After windingthe hoop, the hoop is placed between a pair of press platens whichflatten it under pressure. The platens are then heated to bring theheat-fusible thin plastic film coating between the electrode layers to afusing temperature. During the heating of the capacitor layers, a lightpressure is maintained which is sufficient to exclude air and bring thesurfaces into an intimate contact and yet is low enough to prevent thethin plastic coating from extruding and thus uncontrollably varying itsthickness and thus, its capacitance. After fusion occurs, the pressureis maintained and the platens are cooled, following which the capacitorflat is removed as a solid block.

The capacitor flat is then subjected to a metal spraying operationwherein an oxygen-acetylene flame melts continuously fed aluminum wirewhile a concentric, high velocity, air stream breaks up the moltenaluminum into particles about 0.001 inch in diameter and impels themagainst the thermoplastic capacitor flat. The capacitor flat is thencleared by subjecting it to a DC voltage equivalent to about one quarterof its intended rated DC voltage to burn open any major shorting areas.This procedure is then followed by a high DC voltage, usually twice therated voltage, to complete the clearing process. After clearing thecapacitor flat, its capacitance value is measured since the two ends ofthe flat, which are scrap, can be considered as forming the two halvesof a cylindrical capacitor, the relative area of the cylindricalcapacitor as compared to the flat remaining area can be readily figuredmathematically and its value subtracted from the total value read inorder to permit the capacitance per unit of length of the flat area tobe determined.

The capacitor flat may then be cut into a plurality of identicalindividual chips which will have a very uniform value since the activearea, film thickness and dielectric constant are very uniform within agiven capacitor flat. To achieve a predetermined value of capacitance,the first chip or two cut from a flat may be value sampled and a vernierstop on a cutting mechanism adjusted so that the value of subsequentlycut chips will achieve the predetermined target value. After the chipsare cut, their values may be adjusted slightly downwardly if desired bythe application of a high voltage in order to burn back the electrodesurface and thus reduce the electrode area. Cutting can be done by manytypes of equipment, such as a high speed saw, a hot wire, a high speedfriction blade or a shear. Since each of these cutting techniques wouldpresent the possibility of wiping electrode material between electrodesalong the cut edges, it is necessary to clear the parts again aftercutting to burn open the conductive paths. The additional step ofclearing after cutting can be avoided if the metalized material wound informing the capacitor is appropriately demetalized in those areas wherecutting will take place.

By winding the hoop from which the chips are cut from metalized stripshaving multiple metalized patterns which are staggered transversely, itis possible to achieve a capacitor flat which may be cut in twodirections to form a large plurality of chips.

Where the chips are formed by cutting the flat in two directions, it is,of course, necessary to apply the terminations after the cutting takesplace. This may be done by stacking the cut chips so that one edge ofeach chip lies in a plane which is then subjected to a metal sprayingoperation. By spraying aluminum on the edges of the capacitor containingthe electrode terminals and continuing the spray around an adjacent endand then applying a coating of solder onto the end, it becomes possibleto solder the chip to a tinned substrate pattern by the momentaryaddition of heat and solder in the 10- calized area on the said end edgeof the capacitor. The solder coating permits the connection between themetalized electrodes and the sprayed aluminum to remain cool duringsoldering and thereby minimizes any chance of thermal damage.

In order to enhance the degree of contact of the sprayed aluminumcoatings to the extremely thin electrodes, the capacitor chips may becut on an angle rather than perpendicular to the planes of the electrodelayers. Such angled cutting increases the width of the exposed edgesurface and also presents the electrodes at the edge in step-wisefashion so that the sprayed metal will contact not only the outer edges,but a portion of the marginal length of each electrode.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a cross-section of atwo-side metalized and plastic coated dielectric strip used in makingthe capacitor of the invention;

FIG. 2 is a view similar to FIG. 1 showing a modified form of strip witha marginally recessed plastic coating;

FIG. 3 shows a fragmentary cross-section of a marginal portion of amultilayer stack capacitor made from the strip shown in FIG. I after aspray metal coating has been applied thereto;

FIG. 4 is a view similar to FIG. 3 showing the application of a spraymetal coating to a stack capacitor made from the strip shown in FIG. 2;

FIG. 5 is a perspective view showing the strip material of FIG. I woundinto a hoop;

FIG. 6 is a view illustrating the flattening under pressure of the hoopof FIG. 5;

FIG. 7 is a perspective view showing metal spraying of the marginaledges of a plurality of the flattened hoops shown in FIG. 6;

FIG. 8 is a perspective view illustrating the measuring of thecapacitance of one of the flattened hoops which are metal sprayed inFIG. 7;

FIG. 9 shows a perspective view of a device for cutting the flattenedcapacitor hoop into a plurality of individual chip capacitors;

FIG. 10 is a perspective cross-section taken on the line l010 of FIG. 11showing a multilayer capacitor flat made from a wide web of two-sidemetalized and plastic coated dielectric material which differs from thestrip of FIG. l in that it has multiple metalized patterns adapted to becut longitudinally along the dotted lines;

FIG. Ill is a perspective view of a flattened capacitor hoop wound frommaterial shown in cross-section in FIG. 10 with the cutting linesdotted;

FIG. I2 is a plan view of a modified form of multilayer capacitor flatwith the top layer of plastic removed to expose the electrode plates,which is similar to the capacitor flat of FIG. 10 except that thelongitudinal metalized patterns are interrupted by cleared areas;

FIG. I3 is a cross-sectional view taken on the line I3- l3 of FIG. I4transversely of the length of the dielectric strip;

FIG. 14 is a cross-sectional view taken along the line 14-14 in FIG. 12;

FIG. 15 is a perspective view of a capacitor chip formed by cutting theflattened hoop shown in FIGS. 12-14 in two directions and applying asprayed metal coating to the edges having exposed electrodes;

FIG. 16 is a view similar to 15 showing the application of a sprayedmetal coating not only to the exposed electrodes, but partially aroundone end of the capacitor and the application of a coating of solder tothat portion of the sprayed coating which is not in direct contact withthe electrodes;

FIG. 17 is a longitudinal section through a modified form of multilayercapacitor flat having a series of cleared longitudinal lanes andtransverse cutting lanes which are staggered to present alternateelectrodes;

FIG. 18 is a diagrammatic representation of the application of a sprayedmetal coating to the offset electrodes of capacitor chips cut from thecapacitor flat of FIG. 117; and

FIG. 19 is a perspective view of an individual capacitor chip cut fromthe capacitor flat shown in FIG. 17 and sprayed with metal on itsbeveled ends.

DESCRIPTION or THE PREFERRED EMBODIMENT 7 FIG. ll shows a cross-sectionof a composite film strip indicated generally at 10 from which the chipcapacitor of the invention is formed. The film composite includes adielectric substrate 12 which may be polyester, on the opposite sides ofwhich are deposited evaporated metal coatings 14, 16 of an electrodemetal such as aluminum. The metalized electrode coatings l4 and 16 arethen coated with an extremely thin layer of dielectric 18, 20 such aspolystyrene or polycarbonate plastics which extends to their marginaledges 22, 24. When a plurality of the composite layers 10 are pressedtogether and heated in a manner to be hereinafter described, the thinplastic coatings 18, 20 fuse together to form a monolithic capacitorhaving a much higher capacitance than an ordinary polyester capacitorsince the plastic coatings I8, 20 have a combined dielectric thicknesssubstantially less than the thickness of the substrate l2. Typicalthicknesses of the various materials are 0.0002 inches for the polyestersubstrate, 0.000001 for the metallic electrode layers 14, I6 and0.000025 inches for each of the thin plastic coatings 18, 20.

The composite film strip 10' shown in FIG. 2 is identical to that shownin FIG. I except that the metalized dielectric strip 12' is maskedduring application of the plastic coatings 18, 20' so as to extend shortof the marginal edges 22', 24.

FIGS. 3 and 4 illustrate the cooperation of a sprayed metal coating 40or 40 with the marginal edges 22 or 22' of a multilayer stack ofcomposite layers (FIG. 3) or 10' (FIG. 4). In FIG. 3, it can be seenthat the lower plastic coating on one composite layer 10 has been fusedtogether with the upper plastic layer of the adjacent composite layer 10to form an integral fused coating 19 due to application of heat andpressure to the stack. The sprayed metallic coating 40 can be seen asslightly penetrating the edges of the substrate 12 and much more deeplypenetrating the softer plastic 19 so as to become embedded in it andpenetrate it so as to make contact with portions of the flat surface ofelectrodes 14 as well as their ends. In FIG. 4 it can be seen that thepenetration of the metal spray 40' is somewhat deeper than that in FIG.3 since the plastic coatings 18, 20', and thus the fused coating 19, arerecessed. This embodiment would of course provide substantially moredirect contact between the metal spray particles 40 and the surfaces ofelectrodes 14', but at the expense of providing masking during thecoating of the electrodes.

To form the capacitor of the present invention, a strip of the compositefilm 10 is wound in a plurality of convolutions around either a circularcollapsible mandrel (not shown) so as to form an annular hoop shown inFIG. 5, or about other structure such as a pair of spaced apart pinswhich would provide a rather flattened hoop (not shown). In order tohold the hoop together after winding is completed, the outer convolutionof the hoop 30' may be heat sealed along a line 32 to the adjacentconvolutions. Suitable structure for performing such sealing is shown inU.S. Pat. No. 2,950,070. Although heat sealing, in accordance with theaforementioned U.S. Patent, wherein cutting of the web takes placesimultaneously, eliminates the necessity for a separate cuttingoperation, it is obvious that other methods of sealing and cutting couldbe used, including the use of adhesives or tape.

FIG. 6 illustrates the processing step of compressingas to form acapacitor flat 30. In order to eliminate the seal line 32 from havingany effect on the capacitor chips 30b which are to be cut from the flat30, the hoop 30 is pressed so that the seal line 32 will end up in ascrap area of the flat 30 at one of its ends. To form the flat 30, theplatens 34, 36 are heated so that the plastic layers 18, 20 will beslightly softened so as to flow together and bond to each other withoutaffecting the substrate dielectric material 12. The amount of heat andpressure applied varies, depending on the particular materials used.However, it is important that the pressure and heat be sufficient toexclude air from between the coated layers 18, 20 but not be so great asto cause such layers 18, 20 to extrude outwardly since such a conditioncould cause the metallic layers l6, l4 which they separate to short outor could vary the thickness of the final fused layer 19 so as to alterthe value of individual capacitor chips cut from the flat 30. Afterfusing, the plates 34, 36 are cooled before the pressure is released.

FIG. 7 illustrates the step of applying a metal sprayed coating 40 witha gun 42 to the edges of a plurality of capacitor flats 30 held byclamps 44, 46. The coating 40 becomes embedded in the plastic layers 19as shown in FIGS. 3 and 4 so as to electrically connect each of theelectrode layers at one marginal edge of the flat. In order for theparticles of metal spray 40 to become embedded in the plastic layer 19,and contact not only the tenninal edge portions of the electrodes 14,but also a portion of their flat surfaces, the metal spraying must bedone at rather high velocity. Suitable commercially available materialsand equipment and settings which have proved suitable, are as follows: aMetco 4E Gun, a Metco Flow Meter, and Metco 15 gauge aluminum wire. Thewire is fed at a rate of 13 plus or minus 2 feet per minute with the gunnozzle being approximately 5 /2 inches from the capacitor. During thespraying, the flow meter readings should be approximately 50 for theair, 15 for the oxygen, and 15 for the acetylene. An oxygen-acetyleneflame melts the aluminum wire and a concentric, high velocity, airstream breaks up the molten aluminum into particles about 0.001 inch indiameter and impels the hot particles against the thermoplasticcapacitor flat.

In FIG. 8 the processing step of clearing is illustrated. The capacitorflat 30 is cleared after metal spraying by subjecting it to an ACvoltage passing through the contacts 52, 54 which is equivalent to aboutone-fourth of its intended rated DC voltage. This low impedance sourceburns open any major shorting areas. This procedure is followed by ahigh voltage DC, usually twice the rated voltage, to complete theclearing process.

After clearing the capacitor flat 30, its capacitance value is measuredby apparatus (not shown). Since the two semi-circular ends 30a (FIG. 9)of the capacitor flats 30 combine to form the two halves of acylindrical capacitor which is scrapped, it is a simple mathematicalexercise to compare the cross-section of the scrap capacitor cylinder tothe flat portion remaining after the ends are removed to determine thecapacitance of the elongated remaining flat portion. An additionalcalculation permits the capacitance per unit of length to be determined,which value can be used to determine the width to which the capacitorsshould be cut in cutting apparatus 56 (FIG. 9). The cutting apparatus 56includes a cutter blade 58 which cuts individual capacitor chips 30bfrom a capacitor flat 30 as the capacitor flat is pushed into the bladeby pusher member 60. A vemier stop member 62 permits the width of eachcapacitor chip 30b to be precisely controlled so that successivecapacitors will have substantially identical values. If desired, thefirst few chips cut from a particular capacitor flat 30 may be valuesampled, and the vemier stop 62 readjusted to move the value ofsubsequent chips to center on a predetermined target value. The chipsmay also be adjusted downwardly in value by the application of a highvoltage to burn back the electrode surface, thereby reducing theelectrode area by the desired amount. Although a saw is shown forcutting the capacitor flat, it is obvious that other techniques such asa' hot wire, a high speed friction blade, a shear or other devicecapable of cutting a strip of plastic with a crusty aluminum surface,would be suitable. Since the cutting techniques just mentioned causeelectrode material to be wiped together along the cut edges, it isnecessary to clear the parts again to burn open the conductive paths.

FIGS. 10 and 11 illustrate a more efficient production system wherein awide web of composite film material 110 having metalized patterns 11 3,116 coated with plastic 118, 120 which are continuous in a longitudinaldirection and staggered transversely is stacked so as to form amultilayer flat bonded together by fused layers 119. Longitudinal cutsmade on the lines 131 will produce a plurality of capacitor flats 130which are individually identical to the capacitor flats 30 previouslydiscussed.

FIGS. 12-14 illustrate a system of electrode patterns differing fromFIG. 10 in that the electrodes are interrupted longitudinally so as toprovide clear cutting lanes 132 at regular intervals. This system ofpatterns eliminates the requirement of clearing after severing. To formchip capacitors from the wide web of flat portions 230, the compositestrips 210 can be cut at regular intervals, stacked and then heatpressed and cut. Since the films are transparent except in theirelectrode areas, the system lends itself to photoelectric registrationcontrol. With the electrode pattern system shown in FIGS. 12-14, thefabricated strips may be cut first longitudinally into flats 230,sprayed as in FIG. 7, and then cut transversely into chips as shown inFIG. 15. Or, the fabricated strips may be cut in either direction, thanthe other to provide an unsprayed chip 230b. This unit may then bestacked with hundreds more to spray the edges after cutting so as tocontact the electrodes 214, 216. This latter procedure prevents thecutting operation from breaking any electrical bonds between the sprayedmetal 240 and the evaporated electrodes 2 14 or 216.

FIG. 16 shows a further refinement in the sprayed area which connectsthe sprayed particles 240 to the evaporated electrodes 214 of a chip23012. The sprayed area 240 is carried around the chamfered corner 230aand almost across the end 230d. The electrode edges are sprayed withaluminum, then the portion of aluminum on end 230d is over-sprayed withsolder 241. This procedure allows the end of the capacitor to besoldered to a tinned substrate pattern by the momentary addition of heatand solder in this localized area. The connection between the metalizedelectrodes 214 and the sprayed aluminum 240 remains cool, therebyminimizing any chance of thermal damage to this somewhat tenuousconnection as the capacitor is connected into its substrate position oras lead wires are assembled.

FIGS. 17-19 shows a modified arrangement for producing a chip whichpresents more area to the aluminum spray, thereby giving a contact oflower resistance and higher reliability. The individual composite filmwebs 310 are metalized with clear longitudinal lanes which are stackedin exact register. The transverse clear lanes 332 are staggered topresent alternate electrodes at consecutive cut lines. After thecapacitor flat 330 is cut on an angle in the cleared area 332, theindividual cut chips are stacked as shown in FIG. 18 and metal sprayapplied thereto from a metalizing gun 342. Since, unlike a woundmetalized capacitor, a chip must have every electrode contacted at eachlayer, the beveled cut presents greater electrode area to the spray toincrease the contact area and improve the contact.

FIG. 19 shows a completed beveled chip 33Gb which has a sprayed metalcoating 340 on its exposed elec- .3 trodes and a solder over-spraycoating 341 which functions the same as the coating 241 in FIG. 16. i

I claim:

1. Method of providing terminations on a capacitor body formed of aplurality of layers of a metal-coated dielectric base strip wherein thefacing metal coatings on adjacent base strips are separated from eachother by a layer of plastic dielectric film and have margin portionsextending to opposite edges of said base strip, said layer of plasticdielectric also overlying said margin portions, comprising the steps ofmounting a plurality of capacitor bodies with a marginal edge face ofeach facing in the same direction, and spraying molten metal particlesagainst the edge faces at a velocity sufficiently high to cause saidparticles to penetrate said plastic dielectric film and permit saidparticles to become embedded therein and in contact with marginalsurface portions of said metal coatings thereby providing electricallyconductive terminations for said metal coatings, a substantial portionof which extends from said surface portions, through said film, to saidedge face.

2. Method of making a capacitor comprising the steps of:

metalizing overlapping electrode regions onboth surfaces of a strip ofdielectric material; applying a thin film coating of plastic dielectricwhich is thinner than said strip to at least both said overlappingmetalized regions; pressing a plurality of said metalized and coatedstrips together under heat to laminate and fuse said plastic coatings toeach other, applying a sprayed metal coating to edge faces of saidcapacitor with sufficient velocity for some of the sprayed particles tobecome embedded in the fused plastic coating,and in contact withmarginal surface portions of the electrodes thereby providingelectrically conductive terminations for said metalized regions, asubstantial portion of which extends from said metalized regions,through said plastic coating, to said edge faces.

3. The method of claim 2 wherein said capacitor is wound in a generallyhoop shape and compressed after winding into an elongated form in whichthe major portions of the lengths of each of its layers define a seriesof flat parallel planes, the length of said portions defining said flatplanes being substantially greater than their thickness.

4. The method of claim 3 wherein said major portions of said compressedcapacitor are sub-divided by cutting so as to form a plurality ofdiscrete multilayer chip capacitors.

5. The method of claim 3 wherein the outer convolution of saiddielectric strip is heat sealed to one or more underlying convolutionsand positioned prior to compression of said hoop so as to end up aftercompression at one end of said elongated form.

6. The method of claim 3 wherein said molten particles are sprayedaround one end of said capacitors so as to provide a continuous sprayedband along said marginal edge face and a portion of the end face of saidcapacitor, and a layer of solder applied over the portion of saidsprayed band on said end face.

7. Method of making a multilayer plastic chip capacitor comprising thesteps of convolutely winding a single web of two side metalized plastichaving thin coatings of plastic on its metalized surfaces into a hoophaving a plurality of convolutions of said web, sealing the outerconvolution to the underlying convolutions, compressing said hoop tocause diametrically opposing portions of said hoop to come into contactand to further cause the thin plastic coatings between adjacentconvolutions and between said opposing portions to bond to each otherand exclude air from between said coatings, and cutting said compressedhoop into a plurality of discrete capacitor chips.

8. The method of claim 7 wherein said metalized plastic comprises alongitudinally continuous metallic electrode coating on each side ofsaid web, the electrode coatings on opposite surfaces of said weboverlapping each other except for a margin along one edge, each of saidelectrode coatings being subjected to a metal spraying operation on eachof said margins prior to being cut into said chips.

9. The method of claim 7 wherein said metalized plastic comprises aseries of longitudinally continuous metallic electrode coatings on eachside of said web, the metallic coatings on each web surface beingseparated from each other by a series of cleared lanes in which saidcompressed hoop is cut, the cleared lanes on one side of said web beingpositioned intermediate the cleared lanes on the opposite side.

10. The method of claim 7 wherein said metalized plastic comprises aseries of longitudinal metallic electrode coatings on each side of saidweb, the metallic coatings on each web surface being separated from eachother by a series of longitudinal cleared lanes in which said compressedhoop is cut, the cleared lanes on one side of said web being positionedintermediate the cleared lanes on the opposite side, said metallicelectrode coatings on both sides of said web being interrupted bytransversely arranged aligned cleared areas.

11. The method of claim 10 wherein said hoop is cut initially along saidlongitudinal cleared lanes into a plurality of smaller hoops which aresprayed with metal on their marginal edges and then cut along saidtransversely arranged cleared areas.

12. The method of claim 10 wherein said hoop is out along saidlongitudinal cleared lanes and said transversely arranged cleared areasinto a series of capacitor chips having electrodes extending only toopposite side edges thereof, metal spraying each of said side edges andan adjoining end portion, and applying a coating of solder to said endportion.

13. The method of claim 7 wherein said metalized plastic comprises alongitudinal metallic electrode coating on opposite sides of said web,both edges of said web on each side thereof having cleared margin areas,said electrode coatings on each of the opposite sides of said web havingspaced transversely cleared areas which are positioned intermediate theelectrode coatings on the other side of the web, said webs beingcompressed so that the cleared areas on one web are slightly offsetrelative to the cleared areas in an adjacent layer, and cutting saidcompressed hoop at an acute angle to the plane of said compressed hoopso as to pass through said cleared areas and provide a beveled edge onsaid chips.

2. Method of making a capacitor comprising the steps of: metalizingoverlapping electrode regions on both surfaces of a strip of dielectricmaterial; applying a thin film coating of plastic dielectric which isthinner than said strip to at least both said overlapping metalizedregions; pressing a plurality of said metalized and coated stripstogether under heat to laminate and fuse said plastic coatings to eachother, applying a sprayed metal coating to edge faces of said capacitorwith sufficient velocity for some of the sprayed particles to becomeembedded in the fused plastic coating, and in contact with marginalsurface portions of the electrodes thereby providing electricallyconductive terminations for said metalized regions, a substantialportion of which extends from said metalized regions, through saidplastic coating, to said edge faces.
 3. The method of claim 2 whereinsaid capacitor is wound in a generally hoop shape and compressed afterwinding into an elongated form in which the major portions of thelengths of each of its layers define a series of flat parallel planes,the length of said portions defining said flat planes beingsubstantially greater than their thickness.
 4. The method of claim 3wherein said major portions of said compressed capacitor are sub-dividedby cutting so as to form a plurality of discrete multilayer chipcapacitors.
 5. The method of claim 3 wherein the outer convolution ofsaid dielectric strip is heat sealed to one or more underlyingconvolutions and positioned prior to compression of said hoop so as toend up after compression at one end of said elongated form.
 6. Themethod of claim 3 wherein said molten particles are sprayed around oneend of said capacitors so as to provide a continuous sprayed band alongsaid marginal edge face and a portion of the end face of said capacitor,and a layer of solder applied over the portion of said sprayed band onsaid end face.
 7. Method of making a multilayer plastic chip capacitorcomprising the steps of convolutely winding a single web of two sidemetalized plastic having thin coatings of plastic on its metalizedsurfaces into a hoop having a plurality of convolutions of said web,sealing the outer convolution to the underlying convolutions,compressing said hoop to cause diametrically opposing portions of saidhoop to come into contact and to further cause the thin plastic coatingsbetween adjacent convolutions and between said opposing portions to bondto each other and exclude air from between said coatings, and cuttingsaid compressed hoop into a plurality of discrete capacitor chips. 8.The method of claim 7 wherein said metalized plastic comprises alongitudinally continuous metallic electrode coating on each side ofsaid web, the electrode coatings on opposite surfaces of said weboverlapping each other except for a margin along one edge, each of saidelectrode coatings being subjected to a metal spraying operation on eachof said margins prior to being cut into said chips.
 9. The method ofclaim 7 wherein said metalized plastic comprises a series oflongitudinally continuous metallic electrode coatings on each side ofsaid web, the metallic coatings on each web surface being separated fromeach other by a series of cleared lanes in which said compressed hoop iscut, the cleared lanes on one side of said web being positionedintermediate the cleared lanes on the opposite side.
 10. The method ofclaim 7 wherein said metalized plastic comprises a series oflongitudinal metallic electrode coatings on each side of said web, themetallic coatings on each web surface being separated from each other bya series of longitudinal cleared lanes in which said compressed hoop iscut, the cleared lanes on one side of said web being positionedintermediate the cleared lanes on the opposite side, said metallicelectrode coatings on both sides of said web being interrupted bytransversely arranged aligned cleared areas.
 11. The method of claim 10wherein said hoop is cut initially along said longitudinal cleared lanesinto a plurality of smaller hoops which are sprayed with metal on theirmarginal edges and then cut along said transversely arranged clearedareas.
 12. The method of claim 10 wherein said hoop is cut along saidlongitudinal cleared lanes and said transversely arranged cleared areasinto a series of capacitor chips having electrodes extending only toopposite side edges thereof, metal spraying each of said side edges andan adjoining end portion, and applying a coating of solder to said endportion.
 13. The method of claim 7 wherein said metalized plasticcomprises a longitudinal metallic electrode coating on opposite sides ofsaid web, both edges of said web on each side thereof having clearedmargin areas, said electrode coatings on each of the opposite sides ofsaid web having spaced transversely cleared areas which are positionedintermediate the electrode coatings on the other side of the web, saidwebs being compressed so that the cleared areas on one web are slightlyoffset relative to the cleared areas in an adjacent layer, and cuttingsaid compressed hoop at an acute angle to the plane of said compressedhoop so as to pass through said cleared areas and provide a beveled edGeon said chips.